Not able to do PGI for more qty than the available qty(-ve stock scenario)

Dear SAP Experts,

I want to do Post Goods Issue(VL01N) for more stocks than the available qty(to allow negative stock).I configured negative stock in material level,Valuation area level,Plant level,storage location level.

Now iam able to to Saleas Order for extra quantity.But while doing PGI, it is showing the error"Only 100qty of material available.

what config i have to do?please guide me.

Thnks in advance

lakshmisundarant